When people live longer, societies have to figure out how to ensure they do not end up in poverty and that they can remain active citizens. Elders in poverty mean higher health system costs because poor people have more health problems. Nonetheless, health issues with aging are inevitable regardless of income level.
The Washington Post highlights the graph from the US Department of Health and Human Services below.
What the graph shows is not a surprise: More people growing older means increased Medicare costs. See the graph below (courtesy of Flowing Data) illustrating the average age of members of congress.
When you wonder why policy choices are made about Medicare, look at those in Congress who are close to receiving it.